A conventional fluorescent lamp includes a cylindrical tube having a uniform phosphor coating on its inner surface. Such a lamp emits light with a uniform cylindrical pattern. In some applications, such as backlighting of a display, it is desirable to provide a fluorescent lamp which emits light in a preferred direction. Fluorescent lamps having an aperture which extends axially along the length of the lamp envelope are well known. A reflective coating is applied to the inside surface of the lamp envelope prior to application of the phosphor coating so that substantially all the light generated by the lamp is directed through the aperture. Examples of aperture fluorescent lamps are disclosed in U.S. Pat. No. 3,225,241 issued Dec. 21, 1965 to Spencer et al, U.S. Pat. No. 3,987,331 issued Oct. 19, 1976 to Schreurs, U.S. Pat. No. 3,012,168 issued Dec. 5, 1961 to Ray et al, U.S. Pat. No. 3,275,872 issued Sep. 27, 1966 to Chernin et al, U.S. Pat. No. 3,115,309 issued Dec. 24, 1963 to Spencer et al, U.S. Pat. No. 3,067,351 issued Dec. 4, 1962 to Gungle et al and U.S. Pat. No. 3,717,781 issued Feb. 20, 1973 to Sadoski et al.
In prior art aperture fluorescent lamps, conventional fluorescent lamp connector configurations have been utilized, as shown in U.S. Pat. No. 3,717,781. A conventional fluorescent lamp connector is also disclosed in U.S. Pat. No. 4,692,661 issued Sep. 8, 1987 to Moskowitz et al. Alternate connector arrangements for fluorescent lamps are disclosed in U.S. Pat. No. 2,322,421 issued Jun. 22, 1943 to Cox and U.S. Pat. No. 4,906,891 issued Mar. 6, 1990 to Takagi et al. In aperture fluorescent lamps which utilize the conventional fluorescent lamp connectors, it has been found difficult to accurately orient the aperture in an optical system. None of the known fluorescent lamp connector configurations permit accurate orientation of the aperture, while being adapted to simple, low cost manufacturing techniques.
Arc discharge tubes and miniature incandescent lamps have been fabricated with press seals. In a press seal, the end of an arc tube or a lamp envelope is heated and is pressed together around the electrical leads which connect to the filament or electrode. An example of a baseless incandescent lamp, also referred to a wedge base lamp, which utilizes a press seal is disclosed in U.S. Pat. No. 4,593,958 issued Jun. 10, 1986 to Baba. In addition, so called "twin-tube" fluorescent lamps, which have a U-shaped lamp envelope, have utilized press seals.
It is a general object of the present invention to provide improved fluorescent lamps.
It is another object of the present invention to provide improved subminiature aperture fluorescent lamps.
It is a further object of the present invention to provide aperture fluorescent lamps wherein the aperture can be accurately aligned with an optical system.
It is yet another object of the present invention to provide aperture fluorescent lamps having an alignment surface with a predetermined orientation relative to the aperture.
It is still another object of the present invention to provide aperture fluorescent lamps which are low in cost and easily manufactured.